1. Technical Field
This invention relates to the category of retention clamps used for fittings, such as sanitary fittings. More specifically, it relates to a clamp for positioning and tensioning mating halves of fittings in a conforming way that provides a calibrated compression force and compensates for sanitary fitting deformations produced by non-rigid materials and stress distortions of the fitting dimensions under dynamic load.
2. Background Art
Conventional sanitary fittings were traditionally designed to be made of rigid materials such as stainless steel or glass filled rigid plastics, and held in place by compression clamps also made of rigid metal or rigid plastic clamp assemblies. The common, well-known design consists of two semicircular parts, hingedly connected to each other at a first end and their free ends secured to one another by a threaded stem and nut. Another well-known embodiment utilizes two semicircular sections retained and aligned by an external compression band of plastic or steel about the clamp circumference. An inclined screw hose clamp style closure pulls the opposite ends of a slotted steel band toward one another, reducing the circumference of the band while compressing the object being retained by clamp. A third embodiment commonly known consists of two rigid plastic semicircular halves with a concave external side accommodating a cable tie with predetermined tension markers to approximate cable tension loads. The clamp contains a convex channel profile adapted to accommodate the flange of a sanitary fitting when the fitting halves are disposed inside the clamp in confronting relation to one another.
The primary operating drawback of all such known clamps is that they are designed and constructed of rigid materials for use on rigid material sanitary clamps machined or molded to high precision tolerances. Such clamps require highly symmetrical mating profiles on their contour mating faces between the clamp body and sanitary fitting surfaces. While such precision conditions existed in the traditional sanitary stainless steel market applications, clamping applications now include flexible, single use, disposable sanitary fittings manufactured using non-precision disposable materials. This new class of sanitary fittings represents the predominant market use for high volume, low cost clamping requirements. However, present unique clamping technical requirements and the technical solutions for these unfulfilled needs are not obvious to those trained in the field. Reliable clamping of flexible sanitary fittings is a requirement not met by the prior art, either individually, or taken as a whole at the time the present invention was made.
The primary construction drawback of all known existing clamps is that they are designed and assembled from multiple sub-components, utilizing operating principals that require mechanical construction and assembly while compromising the operating effectiveness of the assembled clamp.
For example, as shown in FIG. 1, a traditional rigid clamp (prior art) with load bearing hinges creates uneven clamping action around a flexible fitting 3. As can be seen at 1 and 2, excessive pressure is created in the main portion of the clamping body away from the hinge and clasp areas, causing the gasket in between the fittings at 1′ and 2′ to bulge out. This causes leaks in the gasket due to the significant variation in applied pressure both at 3′ and 4′ due to insufficient clamping pressure, and at 1′ and 2′ due to gasket protrusion caused by excessive compression and damage to the gasket.
Thus, there is a need for a single-piece, low-cost, flexible clamping device that is adaptable to generate even compression around the new sanitary fittings.